MKIIC+ voltages

[Henz]

Hello. I have a 1984 C+ DRG . Does anyone know what the ballpark voltages should be? My B+ is 522v, C is 507v, D is 497v and D+ is 491v. The plate voltages for power tubes are 525v . And all of the plate voltages are running high on preamp plates. Years ago I recall measuring the plate voltages on the power tubes and they were around 460v. My preamp tubes seem to be running hotter than normal to touch. Is this something that I should be concerned about or is this normal? Oh, and the screen grid (pin 4 of power t ) is 525v as well. It used to be a few volts lower due to the 470 resistor there. It has the 105 PT. Thanks, Jim.

 

[woodbutcher65]

Those voltages seem to be about right for me. That's with the amp operating and all tubes in their sockets, right?

As for the preamp tubes running hot, Mark IIs are known for that. While I can change out a preamp tube with the amp in standby without getting burned on a LOT of amps, on a Mark II and some other Mesas you'd better let that sucker cool off for a minute unless you want your fingerprints scorched off. But in any event the plate structure should NOT be glowing. Only the filament!

 

[Henz]

Thanks for the reply! Yes, that's with all tubes in and powered up. Gotcha on the red plating. I'm currently running two JJ's 6Ca7's in the outer, when I bounce around and put in a couple of old Sylvania 415's, wow, do they get hot!. The 6Ca7's run much cooler. Your input makes me feel at ease. Remember, I'm the guy ( idiot) who accidentally sprayed canned air on my live amp and had the mini excursion. Thanks, Jim.

 

[GJgo]

PT105 plate voltages should be a tad over 500. This is why many current power tubes don't live long in those amps.. Try the TAD 6L6GC-STR.